Toyota tundra third time the engine check light came on within three years! My question is why was the first time the oxygen sensor failed, toyota replaced it free under a recall notification?. and six months after that repair, another oxygen sensor failed and this time toyota charged me over three hundred dollars, now two three seasons later, Jiffylube diagnosed another failed oxygen sensor because the check light came on a few weeks ago! Maybe it is just bad luck but, my friend had a oxygen four hundred repair with dealer shop toyota on his two year old tacoma too! Is it likely that overseas engineering is not aware of these deffects associated with poor united states octane or is it much worse in that we the people are being scammed by a new kind of corp. gobment?. Lastly, I want to reset it before inspection and is there a fuel treatment additive that can clean these sensors to avoid being rippedoff by toyota? Tia, john

Most oxygen sensor DTCs all too often lead to oxygen sensor replacement.
That is because they are VERY frequently misdiagnosed. If there is a code stored for an O2 sensor, that doesn't mean the O2 sensor is at fault. The sensor may get replaced due to a heater circuit code that is actually just an open fuse.
Without knowing the actual codes stored, nor the subsequent diagnosis, I cannot comment on who changed your sensors or why. I personally don't suspect any global scam because of trouble codes being misdiagnosed. And, no, there isn't any magic formula for cleaning O2 sensors.
IF the code is properly fault traced to the sensor, the only repair is to replace.

I know my cigarette lighter socket hasn't been working around the time the engine ck.light came on! So what you are saying is that the jiffylube guy who changed my oil and used a digital tester might have misdiagnosed an OS for a blown dash fuse?. I will ck. All my in dash fuses.. would you know if it is possible for me to reset the engine ck. Light?. I was hoping to do this if need before routine NJMV inspection.I'm not fixing anymore os because I believe this whole thing is a big scam.

So what you are saying is that the jiffylube guy who changed my oil and used a digital tester might have misdiagnosed an OS for a a blown dash fuse?

No, that isn't what I said. Those are different fuses.
What I was trying to say is just because you have a particular sensor fault code doesn't mean that sensor was the actual fault. The circuit needs to be traced following strategy based diagnostics to determine the fault.
What is the code that your vehicle is storing?
Added: No, you can't easily clear the codes yourself. A scan tool is needed.

Well so much for doityourself vehicle maintenance. I wonder if toyota and other foreign imports are deliberately engineering faulty fuel sensor components or is it the united states EPA or other secret agencies in government that allow faulty fuel sensor components to time out on purpose so they can ripoff millions of americans like this? Back in the old days, any car never had this trouble with the EPA!! It is little wonder less and less are supportive of the EPA and other undercover secret service government agencies stalking us both on and off line out of greed. Just my humble opinion about the matter that has been and amazingly still a questionable issue as to who is in charge of this so called safety issue of our environment we share.